6" DuraVent DuraLiner Masonry Thimble with Slip Connector 6DLR-MTSC1 6" DuraLiner Masonry Thimble with Slip Connector is used to penetrate masonry chimney to allow connection of DuraBlack or DVL to DuraLiner. Adaptor must be used to attach the connector pipe to the masonry thimble. Diameter: 6" Allows connection of DuraBlack or DVL to DuraLiner Durable construction .016†304 stainless steel inner liner. Rigid relining pipe: double-walled with 304 stainless steel inner and galvalume outer. Factory insulated between inner and outer walls.